I just listened to Episode 29 of the WordPress podcast - and according to this, the reason there is no user interface is that they didn't want to provide something until users were clear on what they wanted.

IMHO, this is a bad move. Surely a basic UI to fix misspelled tags, etc. is needed? According to the podcast, the only way to rename or delete a tag is to go directly into the database.

They went on to say that without doubt some users will code plugins that will allow you to do some basic management soon, but why wait on something so fundamental such as a basic management screen for the core of WP? I am puzzled to say the least.

Yes I do agree on that part. A basic interface is definitely needed to rename the tags. Not everyone blogging knows how to access phpAdmin and then alter the db values. But then again, looking back, it may actually be a good thing not to rush too many things into the new release.